For example, an exemplary electronic apparatus includes a fixed casing having operations keys and a movable casing which has a liquid crystal display device or the like and is slidable relative to the fixed casing such as a portable phone and a game machine. A sliding mechanism may be installed in this electronic apparatus to enable a slide motion of the movable casing relative to the fixed casing. One type of the sliding mechanism is disclosed in, for example, Patent Document 1.
In this sliding mechanism applied to the electronic apparatus, a spring unit is assembled inside the electronic apparatus. When the movable casing is opened, the movable casing is biased so that the movable casing becomes in a closed state until the movable casing moves to a predetermined position. When the movable casing is opened beyond the predetermined position, the movable casing is biased so that the movable casing becomes in an opened state. Thus, it is possible to improve operability of the electronic apparatus.
Although various types of springs are used for the spring unit, a spring unit applied with a zigzag spring is disclosed in Patent Document 2. When the zigzag spring is used, it is possible to make thinner the spring unit.    [Patent Document 1] Japanese Laid-open Patent Publication No. 2005-210649    [Patent Document 2] Japanese Registered Utility Model No. 3149892